The present invention relates to air belts and to corresponding air belt assemblies that protect passengers in vehicles when, the vehicle crashes, and, more particularly, to air belts and air belt assemblies having a portion inflated by gas from a gas generator.
Japanese Unexamined Patent Publication No. 5-85301 describes a general type of air belt assembly. FIG. 5 is a perspective view showing the air belt assembly of this publication. This air belt assembly 1 includes an air belt 2a, webbing 2a, a lap belt 3, a buckle device 4, a tongue 5, and a through anchor 6. The air belt 2 extends over a passenger""s body diagonally from the right side to the left side. The webbing 2a has one end coupled to the air belt 2. The lap belt 3 extends over a passenger""s body from the right side to the left side. The buckle device 4 is secured to, for example, the vehicle""s floor. The tongue 5 is inserted in the buckle device 4 when the belts are fastened. The through anchor 6 guides the webbing 2a. 
The webbing 2a is formed by a normal type belt such as a typical, prior art seat belt and is slidably guided by the through anchor 6. The other end of the webbing 2a is secured to a seat belt retractor having an emergency locking mechanism (ELR) 7 fixed to the vehicle body. The retractor 7 thus retracts the webbing 2a. The upper end of the air belt 2 is connected to the webbing 2a through, for example, sewing, and the lower end of the air belt 2 is connected to the tongue 5.
The lap belt 3 is formed by a normal type belt such as a typical seat belt. An end of the lap belt 3 is connected to the tongue 5, and the other end of the lap belt 3 is connected to a seal belt retractor (ELR) 8 secured to the vehicle body. A gas generator 9 is coupled to the buckle device 4 and is activated to generate high pressure gas in case of an emergency such as a car crash. A passage extends in the tongue 5 and the buckle device 4 for introducing gas from the gas generator 9 to the air belt 2.
The air belt 2 is formed by a belt-like bag having a relatively large width, which is folded to reduce its width and is encompassed by a cover. The air belt 2 is normally maintained in a belt-like shape. The air belt assembly 1 is used in the same manner as a prior art seat belt assembly. If the gas generator 9 is activated due to, for example, a car crash, the air belt 2 is expanded to protect the passenger, as indicated by the double dotted broken lines.
In this air belt assembly, the air belt 2 has a cylindrical shape having a relatively large diameter when expanded. The interior volume of the air belt 2 is thus increased, and a relatively large amount of gas is needed for fully expanding the air belt 2.
Further, in this air belt assembly, the retractor 7 retracts the webbing 2a, which is connected to the air belt 2. This is because the thickness of the air belt 2 is larger than that of the webbing 2a, and the air belt 2 is hard to pass through the through anchor 6 and retract by means of the retractor 7.
Accordingly, it is an objective of the present invention to provide an air belt having a flat shape when expanded.
Accordingly, it is another objective of the present invention to eliminate the webbing 2a and to provide an air belt having a belt formed integrally with an expandable portion of the air belt that is passed through a through anchor and is retracted directly by a retractor.
An air belt of the present invention includes a belt having a hollow expandable portion and a bag provided in the expandable portion of the belt. The air belt is expanded by introducing gas in the bag. The air belt is characterized in that each side of the expandable portion in a width direction is an easily expanding portion and that an intermediate portion of the expandable portion in the width direction is a hardly expanding portion.
When gas is introduced in the bag of this air belt, only the opposite sides of the belt are expanded sideward. The air belt is thus expanded in a flat shape. The amount of the gas needed to expand this air belt is less than the amount of the gas needed to expand the prior art cylindrical air belt. Further, the bag is minimized, and the air belt becomes lighter. The air belt also becomes thinner.
The air belt of the present invention includes a solid portion that is smoothly passed through an anchor. Further, a retractor smoothly retracts and extends the air belt.
It is preferred that the width of the expandable portion of the air belt according to the present invention is larger than the width of the non-expandable portion when the expandable portion is not expanded and that the width of the air belt is gradually reduced from the expandable portion to the non-expandable portion. The solid portion of the air belt having a relatively small width is thus smoothly passed through the through anchor and is retracted and extended smoothly by the retractor. The air belt becomes smaller gradually from the expandable portion having a relatively large width to the non-expandable portion having a relatively small width. This structure eliminates a portion on which reactive force concentrates or which is freely movable (such as a projection having a movable distal end), thus improving the durability of the air belt.
In this case, it is preferred that the width of the hardly expanding portion of the expandable portion is substantially equal to the width of the non-expandable portion. It is thus easy to form the air belt as an integral woven structure extending continuously from the hardly expanding portion of the expandable portion to the non-expandable portion.
The width of the expandable portion may be larger than the width of the non-expandable portion by one to two centimeters.
An air belt of the present Invention includes a belt having a hollow expandable portion and a bag provided in the expandable portion of the belt. The air belt is expanded by introducing gas in the bag. The air belt is characterized in that the belt extends continuously from one end of the air belt to the other and that a non-expandable portion formed at the other end of the belt is formed by a solid belt.
An air belt assembly of the present invention includes this air belt expanded by means of a gas generator.
It is preferred that the non-expandable portion of this air belt assembly is passed through a through anchor or is inserted in an air belt insert. The air belt assembly is installed in a vehicle such as an automobile, together with a tongue, to which one end of the air belt is connected, and a retractor retracting the other end of the air belt.